The present invention relates to a muffler for a fan and, more particularly, to a muffler for a by-pass fan of an internal combustion engine with a regulated three-way catalytic converter.
A bypass air fan is used in an internal combustion engine with a regulated three-way catalytic converter to feed fresh air into the exhaust system of the internal combustion engine. Because of that an afterburning of the exhaust gas at temperatures above 600.degree. C. occurs. During the afterburning the carbon monoxide and hydrocarbon content of the exhaust gas is reduced before the exhaust gas flows through the catalytic converter. Furthermore additional heat is supplied to the catalytic converter by the combustion process, which is especially advantageous for cold starts. However at the entrance of this type of bypass air fan considerable noise is generated in operation, which requires the use of a noise damping device, i.e. a so-called muffler, having a housing and an inlet and outlet opening.